Want to make my 40 day old child fly.

All the suggestion are fine. But during take off and landing Please avoid feeding, it may cause aspiration. During journey  cabin crew also give some safety instructions.

yes can travel Cnhanging cabin pressure during a flight causes temporary changes in middle ear pressure, which can trigger ear pain. To help equalize the pressure in your baby's ears, offer your baby a breast, bottle or pacifier to suck on during takeoff and the initial descent. It might help to try to time your baby's feedings so that he or she is hungry during these times. Also, airplane cabin noise levels are loud, especially during takeoff. Consider using cotton balls, noise-canceling headphones or small earplugs to limit your baby's exposure to this noise and make it easier for him or her to sleep. Your baby's breathing. During flight, air pressure in an aircraft cabin is lower than air pressure on land. This temporary change in oxygen level doesn't seem to pose problems for otherwise healthy babies. Your baby's safety seat. Most infant car seats are certified for air travel. Although airlines typically allow infants to ride on a caregiver's lap during flight, the Federal Aviation Administration recommends that infants ride in properly secured safety seats. If you choose not to purchase a ticket for your infant, ask about open seats when you board the plane — in case one can be assigned to your infant. Don't be tempted to give your baby an over-the-counter medication, such as diphenhydramine (Benadryl, others), to encourage sleep during the flight. The practice isn't recommended, and sometimes the medication can have the opposite effect

travel with safety measures

Just breastfeed ur baby during take off and landing...no problem otherwise

That is correct... No problems in flying

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